1. Field of the Invention
The invention relates to a gel for sealing holes for waterproofing stitched footwear.
2. Discussion of the Prior Art
In the manufacture of footwear products, one of the manufacturing steps for many of these products is a stitching step wherein two materials of the footwear construction are joined together by a needle carrying thread through the hole caused by the needle. There are several footwear manufacturing processes that stitch materials together, for example, the well known basic welt process, modified welt process, the littleway process, the triple (or double) needle process, the stitchdown process and the sidewall process.
In the welt process, an insole rib is attached to an insole. The inner surface of the rib defines a rib cavity. A welt is stitched to an upper and to the outer surface of the insole rib, typically by chain stitches. Normally, a lining is interposed between the upper and the rib.
Historically, the problem with welt shoes is that they leak, that is they are not waterproof, unless they are manufactured with a full waterproof bootie or double lasted with a waterproof membrane. The problem with these systems is that not only do they encourage heat build-up inside the shoe but they also increase the weight and cost of the shoes. In welted footwear the xe2x80x98leakingxe2x80x99 is primarily through the holes formed by the needle during chain stitching and water seeping into the footwear from the rib cavity. Similarly, with the other types of stitched constructions, leaking is a problem and the current techniques used to waterproof the stitched areas reduce the breathability of the material and/or are not aesthetically pleasing.
The sealants of the invention overcome this leaking by sealing the holes formed during stitching.
Broadly the invention comprises applying a gel-like sealant to at least one surface of a first footwear component which is to be joined to a second piece of footwear component by stitching. The needle passes through the first footwear component, the gel and the second footwear component to stitch the materials together. After the needle withdraws, the gel seals the stitched hole caused by the needle.
The preferred embodiment of the invention will be described with reference to the basic welted footwear construction. Alternative embodiments of the invention employ the gel for stitching in the modified welt process, littleway process, the triple needle process, the stitchdown process and/or the sidewall process.
An upper footwear assembly usually comprises an upper and a lining which are stitched to the insole rib, in the same stitching step which attaches the welt to the rib.
In the system of the invention, a sealing gel, preferably in the form of a bead, is placed along the outer surface of the rib prior to stitching the welt/upper/liner/rib. When these materials are stitched, the needle carries the gel into the holes and seals the holes formed in the welt/upper/liner/rib. This blocks any water from entering the footwear through the needle holes of the chain stitching.
Although the gel seals the holes formed, the construction is still a sandwiched construction of welt/upper/lining/rib. It is possible for water to seep between the upper and the lining. Accordingly, in another aspect of the invention, prior to stitching the welt/upper/lining to the rib, the sealing gel, preferably in the form of a tape, is placed between the upper and the lining. The tape can be placed so that it overlays the stitch line or is just above the stitch line.
In welted footwear construction the heel assemblies vary and the rib may not extend along the entire perimeter of the inner sole. Different manufacturing steps are employed to fasten the heel to the sole. For example the rib and welt may be trimmed away at the heel and the upper/lining fastened directly to the inner sole. In this embodiment, the sealing gel (tape) is still used between the upper and the lining. Where the upper and lining are nailed to the inner sole on the heel section, the sealing gel, preferably in the form of a flat gasket, is placed under the heel section of the inner sole and then the upper/tape/lining is fastened to the inner sole.
Lastly, in the system of the invention a liquid sealant is coated in the cavity defined by the rib, specifically by applying a sealer inside the rib cavity and on the top of the rib after inseaming (attaching the welt to the insole and trimming).